地应力弹性参数计算的应力区间分级方法研究

A STRESS INTERVAL CLASSIFICATION METHOD FOR CALCULATING ROCK ELASTIC PARAMETERS IN IN-SITU STRESS MEASUREMENT

对套孔应力解除法地应力现场测量获得的套孔岩芯进行围压率定试验,是后期数据处理获取岩石弹性参数的重要手段,其结果直接影响地应力计算值的精度。目前,参与地应力计算的弹性参数由围压试验中的最高围压值与对应的应变计算获得,受试验条件、岩石的非线性影响,结果存在一定的误差。利用围压率定仪对多组套孔岩芯试样进行率定试验,研究不同岩性岩石围压率定试验曲线特征规律;基于多重误差因素分析,对试验应力应–变曲线进行合理修正。结合岩石的加卸载变形理论,考虑岩石非线性特征,提出一种将弹性参数划分成不同应力区间计算的方法。将该方法运用到平煤十矿(平顶山天安煤业股份有限公司十矿)实测地应力的计算中,修正后的主应力计算结果随深度呈现出更好的线性相关性,与实际情况符合较好,研究成果对提高套孔岩芯弹性参数及实测地应力的计算结果精度具有一定的参考意义。

Confining pressure test for trepanning core acquired from in-situ stress measurement is an important means to obtain rock elastic parameters in in-situ stress calculation. The testing results and data processing play an important role in precision of final in-situ stress value. At present,rock elastic parameters are usually calculated on the basis of stress and strain under highest pressure in testing,which could lead to major error owing to rock nonlinear characteristics and test conditions. Confining pressure tests including multiple specimens are implemented by means of confining pressure instrument. Testing results are reasonable which are modified through analysis of testing curve law and consider multiple error factors. Based on loading unloading deformation theory of rock and rock nonlinearity,a calculation method in which elastic parameters are divided by different stress intervals is put forward. In-situ stress calculation example of No.10 mine of Pingdingshan Tian?an coal mine Co.,Ltd. is used to verify this method. The results reveal that linear correlation of calculated stress value and depth is more significant,which will provide references to improvement of in-situ stress calculation accuracy.